Relationship Between Census Tract-Level Poverty and Domestically Acquired Salmonella Incidence: Analysis of Foodborne Diseases Active Surveillance Network Data, 2010-2016.

BACKGROUND: The relationships between socioeconomic status and domestically acquired salmonellosis and leading Salmonella serotypes are poorly understood. METHODS: We analyzed surveillance data from laboratory-confirmed cases of salmonellosis from 2010-2016 for all 10 Foodborne Disease Active Surveillance Network (FoodNet) sites, having a catchment population of 47.9 million. Case residential data were geocoded, linked to census tract poverty level, and then categorized into 4 groups according to census tract poverty level. After excluding those reporting international travel before illness onset, age-specific and age-adjusted salmonellosis incidence rates were calculated for each census tract poverty level, overall and for each of the 10 leading serotypes. RESULTS: Of 52 821geocodable Salmonella infections (>96%), 48 111 (91.1%) were domestically acquired. Higher age-adjusted incidence occurred with higher census tract poverty level (P < .001; relative risk for highest [≥20%] vs lowest [<5%] census tract poverty level, 1.37). Children <5 years old had the highest relative risk (2.07). Although this relationship was consistent by race/ethnicity and by serotype, it was not present in 5 FoodNet sites or among those aged 18-49 years. CONCLUSION: Children and older adults living in higher-poverty census tracts have had a higher incidence of domestically acquired salmonellosis. There is a need to understand socioeconomic status differences for risk factors for domestically acquired salmonellosis by age group and FoodNet site to help focus prevention efforts.

Preliminary Incidence and Trends of Infections with Pathogens Transmitted Commonly Through Food - Foodborne Diseases Active Surveillance Network, 10 U.S. Sites, 2015-2018.

Foodborne diseases represent a major health problem in the United States. The Foodborne Diseases Active Surveillance Network (FoodNet) of CDC's Emerging Infections Program monitors cases of laboratory-diagnosed infection caused by eight pathogens transmitted commonly through food in 10 U.S. sites.* This report summarizes preliminary 2018 data and changes since 2015. During 2018, FoodNet identified 25,606 infections, 5,893 hospitalizations, and 120 deaths. The incidence of most infections is increasing, including those caused by Campylobacter and Salmonella, which might be partially attributable to the increased use of culture-independent diagnostic tests (CIDTs). The incidence of Cyclospora infections increased markedly compared with 2015-2017, in part related to large outbreaks associated with produce (1). More targeted prevention measures are needed on produce farms, food animal farms, and in meat and poultry processing establishments to make food safer and decrease human illness.

Differences Among Incidence Rates of Invasive Listeriosis in the U.S. FoodNet Population by Age, Sex, Race/Ethnicity, and Pregnancy Status, 2008-2016.

Listeria monocytogenes is a foodborne pathogen that disproportionally affects pregnant females, older adults, and immunocompromised individuals. Using U.S. Foodborne Diseases Active Surveillance Network (FoodNet) surveillance data, we examined listeriosis incidence rates and rate ratios (RRs) by age, sex, race/ethnicity, and pregnancy status across three periods from 2008 to 2016, as recent incidence trends in U.S. subgroups had not been evaluated. The invasive listeriosis annual incidence rate per 100,000 for 2008-2016 was 0.28 cases among the general population (excluding pregnant females), and 3.73 cases among pregnant females. For adults ≥70 years, the annual incidence rate per 100,000 was 1.33 cases. No significant change in estimated listeriosis incidence was found over the 2008-2016 period, except for a small, but significantly lower pregnancy-associated rate in 2011-2013 when compared with 2008-2010. Among the nonpregnancy-associated cases, RRs increased with age from 0.43 (95% confidence interval: 0.25-0.73) for 0- to 14-year olds to 44.9 (33.5-60.0) for ≥85-year olds, compared with 15- to 44-year olds. Males had an incidence of 1.28 (1.12-1.45) times that of females. Compared with non-Hispanic whites, the incidence was 1.57 (1.18-1.20) times higher among non-Hispanic Asians, 1.49 (1.22-1.83) among non-Hispanic blacks, and 1.73 (1.15-2.62) among Hispanics. Among females of childbearing age, non-Hispanic Asian females had 2.72 (1.51-4.89) and Hispanic females 3.13 (2.12-4.89) times higher incidence than non-Hispanic whites. We observed a higher percentage of deaths among older patient groups compared with 15- to 44-year olds. This study is the first characterizing higher RRs for listeriosis in the United States among non-Hispanic blacks and Asians compared with non-Hispanic whites. This information for public health risk managers may spur further research to understand if differences in listeriosis rates relate to differences in consumption patterns of foods with higher contamination levels, food handling practices, comorbidities, immunodeficiencies, health care access, or other factors.

Preliminary Incidence and Trends of Infections with Pathogens Transmitted Commonly Through Food - Foodborne Diseases Active Surveillance Network, 10 U.S. Sites, 2006-2017.

Despite ongoing food safety measures in the United States, foodborne illness continues to be a substantial health burden. The 10 U.S. sites of the Foodborne Diseases Active Surveillance Network (FoodNet)* monitor cases of laboratory-diagnosed infections caused by nine pathogens transmitted commonly through food. This report summarizes preliminary 2017 data and describes changes in incidence since 2006. In 2017, FoodNet reported 24,484 infections, 5,677 hospitalizations, and 122 deaths. Compared with 2014-2016, the 2017 incidence of infections with Campylobacter, Listeria, non-O157 Shiga toxin-producing Escherichia coli (STEC), Yersinia, Vibrio, and Cyclospora increased. The increased incidences of pathogens for which testing was previously limited might have resulted from the increased use and sensitivity of culture-independent diagnostic tests (CIDTs), which can improve incidence estimates (1). Compared with 2006-2008, the 2017 incidence of infections with Salmonella serotypes Typhimurium and Heidelberg decreased, and the incidence of serotypes Javiana, Infantis, and Thompson increased. New regulatory requirements that include enhanced testing of poultry products for Salmonella† might have contributed to the decreases. The incidence of STEC O157 infections during 2017 also decreased compared with 2006-2008, which parallels reductions in isolations from ground beef.§ The declines in two Salmonella serotypes and STEC O157 infections provide supportive evidence that targeted control measures are effective. The marked increases in infections caused by some Salmonella serotypes provide an opportunity to investigate food and nonfood sources of infection and to design specific interventions.

Multicenter Evaluation of Clinical Diagnostic Methods for Detection and Isolation of Campylobacter spp. from Stool.

The use of culture-independent diagnostic tests (CIDTs), such as stool antigen tests, as standalone tests for the detection of Campylobacter in stool is increasing. We conducted a prospective, multicenter study to evaluate the performance of stool antigen CIDTs compared to culture and PCR for Campylobacter detection. Between July and October 2010, we tested 2,767 stool specimens from patients with gastrointestinal illness with the following methods: four types of Campylobacter selective media, four commercial stool antigen assays, and a commercial PCR assay. Illnesses from which specimens were positive by one or more culture media or at least one CIDT and PCR were designated "cases." A total of 95 specimens (3.4%) met the case definition. The stool antigen CIDTs ranged from 79.6% to 87.6% in sensitivity, 95.9 to 99.5% in specificity, and 41.3 to 84.3% in positive predictive value. Culture alone detected 80/89 (89.9% sensitivity) Campylobacter jejuni/Campylobacter coli-positive cases. Of the 209 noncases that were positive by at least one CIDT, only one (0.48%) was positive by all four stool antigen tests, and 73% were positive by just one stool antigen test. The questionable relevance of unconfirmed positive stool antigen CIDT results was supported by the finding that noncases were less likely than cases to have gastrointestinal symptoms. Thus, while the tests were convenient to use, the sensitivity, specificity, and positive predictive value of Campylobacter stool antigen tests were highly variable. Given the relatively low incidence of Campylobacter disease and the generally poor diagnostic test characteristics, this study calls into question the use of commercially available stool antigen CIDTs as standalone tests for direct detection of Campylobacter in stool.

Infection with Pathogens Transmitted Commonly Through Food and the Effect of Increasing Use of Culture-Independent Diagnostic Tests on Surveillance--Foodborne Diseases Active Surveillance Network, 10 U.S. Sites, 2012-2015.

To evaluate progress toward prevention of enteric and foodborne illnesses in the United States, the Foodborne Diseases Active Surveillance Network (FoodNet) monitors the incidence of laboratory-confirmed infections caused by nine pathogens transmitted commonly through food in 10 U.S. sites. This report summarizes preliminary 2015 data and describes trends since 2012. In 2015, FoodNet reported 20,107 confirmed cases (defined as culture-confirmed bacterial infections and laboratory-confirmed parasitic infections), 4,531 hospitalizations, and 77 deaths. FoodNet also received reports of 3,112 positive culture-independent diagnostic tests (CIDTs) without culture-confirmation, a number that has markedly increased since 2012. Diagnostic testing practices for enteric pathogens are rapidly moving away from culture-based methods. The continued shift from culture-based methods to CIDTs that do not produce the isolates needed to distinguish between strains and subtypes affects the interpretation of public health surveillance data and ability to monitor progress toward prevention efforts. Expanded case definitions and strategies for obtaining bacterial isolates are crucial during this transition period.

Socioeconomic Status and Foodborne Pathogens in Connecticut, USA, 2000-2011(1).

Foodborne pathogens cause >9 million illnesses annually. Food safety efforts address the entire food chain, but an essential strategy for preventing foodborne disease is educating consumers and food preparers. To better understand the epidemiology of foodborne disease and to direct prevention efforts, we examined incidence of Salmonella infection, Shiga toxin-producing Escherichia coli infection, and hemolytic uremic syndrome by census tract-level socioeconomic status (SES) in the Connecticut Foodborne Diseases Active Surveillance Network site for 2000-2011. Addresses of case-patients were geocoded to census tracts and linked to census tract-level SES data. Higher census tract-level SES was associated with Shiga toxin-producing Escherichia coli, regardless of serotype; hemolytic uremic syndrome; salmonellosis in persons ≥5 years of age; and some Salmonella serotypes. A reverse association was found for salmonellosis in children <5 years of age and for 1 Salmonella serotype. These findings will inform education and prevention efforts as well as further research.

Postdiarrheal hemolytic uremic syndrome in United States children: clinical spectrum and predictors of in-hospital death.

OBJECTIVE: To assess the clinical spectrum of postdiarrheal hemolytic uremic syndrome (D(+)HUS) hospitalizations and sought predictors of in-hospital death to help identify children at risk of poor outcomes. STUDY DESIGN: We assessed clinical variables collected through population-based surveillance of D(+)HUS in children <18 years old hospitalized in 10 states during 1997-2012 as predictors of in-hospital death by using tree modeling. RESULTS: We identified 770 cases. Of children with information available, 56.5% (430 of 761) required dialysis, 92.6% (698 of 754) required a transfusion, and 2.9% (22 of 770) died; few had a persistent dialysis requirement (52 [7.3%] of 716) at discharge. The tree model partitioned children into 5 groups on the basis of 3 predictors (highest leukocyte count and lowest hematocrit value during the 7 days before to 3 days after the diagnosis of hemolytic uremic syndrome, and presence of respiratory tract infection [RTI] within 3 weeks before diagnosis). Patients with greater leukocyte or hematocrit values or a recent RTI had a greater probability of in-hospital death. The largest group identified (n = 533) had none of these factors and had the lowest odds of death. Many children with RTI had recent antibiotic treatment for nondiarrheal indications. CONCLUSION: Most children with D(+)HUS have good hospitalization outcomes. Our findings support previous reports of increased leukocyte count and hematocrit as predictors of death. Recent RTI could be an additional predictor, or a marker of other factors such as antibiotic exposure, that may warrant further study.

Bacterial enteric infections detected by culture-independent diagnostic tests--FoodNet, United States, 2012-2014.

The increased availability and rapid adoption of culture-independent diagnostic tests (CIDTs) is moving clinical detection of bacterial enteric infections away from culture-based methods. These new tests do not yield isolates that are currently needed for further tests to distinguish among strains or subtypes of Salmonella, Campylobacter, Shiga toxin-producing Escherichia coli, and other organisms. Public health surveillance relies on this detailed characterization of isolates to monitor trends and rapidly detect outbreaks; consequently, the increased use of CIDTs makes prevention and control of these infections more difficult. During 2012-2013, the Foodborne Diseases Active Surveillance Network (FoodNet*) identified a total of 38,666 culture-confirmed cases and positive CIDT reports of Campylobacter, Salmonella, Shigella, Shiga toxin-producing E. coli, Vibrio, and Yersinia. Among the 5,614 positive CIDT reports, 2,595 (46%) were not confirmed by culture. In addition, a 2014 survey of clinical laboratories serving the FoodNet surveillance area indicated that use of CIDTs by the laboratories varied by pathogen; only CIDT methods were used most often for detection of Campylobacter (10%) and STEC (19%). Maintaining surveillance of bacterial enteric infections in this period of transition will require enhanced surveillance methods and strategies for obtaining bacterial isolates.

Modelling counterfactual incidence during the transition towards culture-independent diagnostic testing.

BACKGROUND: Culture-independent diagnostic testing (CIDT) provides rapid results to clinicians and is quickly displacing traditional detection methods. Increased CIDT use and sensitivity likely result in higher case detection but might also obscure infection trends. Severe illness outcomes, such as hospitalization and death, are likely less affected by changes in testing practices and can be used as indicators of the expected case incidence trend had testing methods not changed. METHODS: Using US Foodborne Diseases Active Surveillance Network data during 1996-2019 and mixed effects quasi-Poisson regression, we estimated the expected yearly incidence for nine enteric pathogens. RESULTS: Removing the effect of CIDT use, CIDT panel testing and culture-confirmation of CIDT testing, the modelled incidence in all but three pathogens (Salmonella, Shigella, STEC O157) was significantly lower than the observed and the upward trend in Campylobacter was reversed from an observed 2.8% yearly increase to a modelled -2.8% yearly decrease (95% credible interval: -4.0, -1.4). CONCLUSIONS: Severe outcomes may be useful indicators in evaluating trends in surveillance systems that have undergone a marked change.

Population-based active surveillance for Cyclospora infection--United States, Foodborne Diseases Active Surveillance Network (FoodNet), 1997-2009.

BACKGROUND: Cyclosporiasis is an enteric disease caused by the parasite Cyclospora cayetanensis. Since the mid-1990 s, the Centers for Disease Control and Prevention has been notified of cases through various reporting and surveillance mechanisms. METHODS: We summarized data regarding laboratory-confirmed cases of Cyclospora infection reported during 1997-2009 via the Foodborne Diseases Active Surveillance Network (FoodNet), which gradually expanded to include 10 sites (Connecticut, Georgia, Maryland, Minnesota, New Mexico, Oregon, Tennessee, and selected counties in California, Colorado, and New York) that represent approximately 15% of the US population. Since 2004, the number of sites has remained constant and data on the international travel history and outbreak status of cases have been collected. RESULTS: A total of 370 cases were reported, 70.3% (260) of which were in residents of Connecticut (134 [36.2%]) and Georgia (126 [34.1%]), which on average during this 13-year period accounted for 29.0% of the total FoodNet population under surveillance. Positive stool specimens were collected in all months of the year, with a peak in June and July (208 cases [56.2%]). Approximately half (48.6%) of the 185 cases reported during 2004-2009 were associated with international travel, known outbreaks, or both. CONCLUSIONS: The reported cases were concentrated in time (spring and summer) and place (2 of 10 sites). The extent to which the geographic concentration reflects higher rates of testing, more sensitive testing methods, or higher exposure/infection rates is unknown. Clinicians should include Cyclospora infection in the differential diagnosis of prolonged or relapsing diarrheal illness and explicitly request stool examinations for this parasite.

Impacts of culture-independent diagnostic practices on public health surveillance for bacterial enteric pathogens.

For decades, culture has been the mainstay of diagnostic testing for bacterial enteric pathogens. This paradigm is changing as clinical laboratories adopt culture-independent methods, such as antigen-based tests and nucleic acid-based assays. Public health surveillance for enteric infections addresses 4 interrelated but distinct objectives: case investigation for localized disease control; assessment of disease burden and trends to prioritize and assess impact of population-based control measures; outbreak detection; and microbiologic characterization to improve understanding of pathogens, their virulence mechanisms, and epidemiology. We summarize the challenges and opportunities that culture-independent tests present and suggest strategies, such as validation studies and development of culture-independent tests compatible with subtyping, that could be adopted to ensure that surveillance remains robust. Many of these approaches will require time and resources to implement, but they will be necessary to maintain a strong surveillance system. Public health practitioners must clearly explain the value of surveillance, especially how outbreak detection benefits the public, and collaborate with all stakeholders to develop solutions.

Clinical laboratory practices for the isolation and identification of Campylobacter in Foodborne Diseases Active Surveillance Network (FoodNet) sites: baseline information for understanding changes in surveillance data.

BACKGROUND: Campylobacter is a leading cause of foodborne illness in the United States. Understanding laboratory practices is essential to interpreting incidence and trends in reported campylobacteriosis over time and provides a baseline for evaluating the increasing use of culture-independent diagnostic methods for Campylobacter infection. METHODS: The Foodborne Diseases Active Surveillance Network (FoodNet) conducts surveillance for laboratory-confirmed Campylobacter infections. In 2005, FoodNet conducted a survey of clinical laboratories to describe routine practices used for isolation and identification of Campylobacter. A profile was assigned to laboratories based on complete responses to key survey questions that could impact the recovery and isolation of Campylobacter from stool specimens. RESULTS: Of 411 laboratories testing on-site for Campylobacter, 97% used only culture methods. Among those responding to the individual questions, nearly all used transport medium (97%) and incubated at 42°C (94%); however, most deviated from existing guidelines in other areas: 68% held specimens in transport medium at room temperature before plating, 51% used Campy blood agar plate medium, 52% read plates at <72 hours of incubation, and 14% batched plates before placing them in a microaerobic environment. In all, there were 106 testing algorithms among 214 laboratories with a complete profile; only 16 laboratories were fully adherent to existing guidelines. CONCLUSIONS: Although most laboratories used culture-based methods, procedures differed widely and most did not adhere to existing guidelines, likely resulting in underdiagnosis. Given the availability of new culture-independent testing methods, these data highlight a clear need to develop best practice recommendations for Campylobacter infection diagnostic testing.

Validating deaths reported in the Foodborne Diseases Active Surveillance Network (FoodNet): are all deaths being captured?

Accurate information about deaths is important when determining the human health and economic burden of foodborne diseases. We reviewed death certificate data to assess the accuracy of deaths reported to the Foodborne Diseases Active Surveillance Network (FoodNet). Data were highly accurate, and few deaths were missed through active surveillance.

Strategies for surveillance of pediatric hemolytic uremic syndrome: Foodborne Diseases Active Surveillance Network (FoodNet), 2000-2007.

BACKGROUND: Postdiarrheal hemolytic uremic syndrome (HUS) is the most common cause of acute kidney failure among US children. The Foodborne Diseases Active Surveillance Network (FoodNet) conducts population-based surveillance of pediatric HUS to measure the incidence of disease and to validate surveillance trends in associated Shiga toxin-producing Escherichia coli (STEC) O157 infection. METHODS: We report the incidence of pediatric HUS, which is defined as HUS in children <18 years. We compare the results from provider-based surveillance and hospital discharge data review and examine the impact of different case definitions on the findings of the surveillance system. RESULTS: During 2000-2007, 627 pediatric HUS cases were reported. Fifty-two percent of cases were classified as confirmed (diarrhea, anemia, microangiopathic changes, low platelet count, and acute renal impairment). The average annual crude incidence rate for all reported cases of pediatric HUS was 0.78 per 100,000 children <18 years. Regardless of the case definition used, the year-to-year pattern of incidence appeared similar. More cases were captured by provider-based surveillance (76%) than by hospital discharge data review (68%); only 49% were identified by both methods. CONCLUSIONS: The overall incidence of pediatric HUS was affected by key characteristics of the surveillance system, including the method of ascertainment and the case definitions. However, year-to-year patterns were similar for all methods examined, suggesting that several approaches to HUS surveillance can be used to track trends.

Assessment of physician knowledge and practices concerning Shiga toxin-producing Escherichia coli infection and enteric illness, 2009, Foodborne Diseases Active Surveillance Network (FoodNet).

BACKGROUND: Shiga toxin-producing Escherichia coli (STEC) infections cause acute diarrheal illness and sometimes life-threatening hemolytic uremic syndrome (HUS). Escherichia coli O157 is the most common STEC, although the number of reported non-O157 STEC infections is growing with the increased availability and use of enzyme immunoassay testing, which detects the presence of Shiga toxin in stool specimens. Prompt and accurate diagnosis of STEC infection facilitates appropriate therapy and may improve patient outcomes. METHODS: We mailed 2400 surveys to physicians in 8 Foodborne Diseases Active Surveillance Network (FoodNet) sites to assess their knowledge and practices regarding STEC testing, treatment, and reporting, and their interpretation of Shiga toxin test results. RESULTS: Of 1102 completed surveys, 955 were included in this analysis. Most (83%) physicians reported often or always ordering a culture of bloody stool specimens; 49% believed that their laboratory routinely tested for STEC O157, and 30% believed that testing for non-O157 STEC was also included in a routine stool culture. Forty-two percent of physicians were aware that STEC, other than O157, can cause HUS, and 34% correctly interpreted a positive Shiga toxin test result. All STEC knowledge-related factors were strongly associated with correct interpretation of a positive Shiga toxin test result. CONCLUSIONS: Identification and management of STEC infection depends on laboratories testing for STEC and physicians ordering and correctly interpreting results of Shiga toxin tests. Although overall knowledge of STEC was low, physicians who had more knowledge were more likely to correctly interpret a Shiga toxin test result. Physician knowledge of STEC may be modifiable through educational interventions.

Invasive listeriosis in the Foodborne Diseases Active Surveillance Network (FoodNet), 2004-2009: further targeted prevention needed for higher-risk groups.

BACKGROUND: Listeriosis can cause severe disease, especially in fetuses, neonates, older adults, and persons with certain immunocompromising and chronic conditions. We summarize US population-based surveillance data for invasive listeriosis from 2004 through 2009. METHODS: We analyzed Foodborne Diseases Active Surveillance Network (FoodNet) data for patients with Listeria monocytogenes isolated from normally sterile sites. We describe the epidemiology of listeriosis, estimate overall and specific incidence rates, and compare pregnancy-associated and nonpregnancy-associated listeriosis by age and ethnicity. RESULTS: A total of 762 listeriosis cases were identified during the 6-year reporting period, including 126 pregnancy-associated cases (17%), 234 nonpregnancy-associated cases(31%) in patients aged <65 years, and 400 nonpregnancy-associated cases (53%) in patients aged ≥ 65 years. Eighteen percent of all cases were fatal. Meningitis was diagnosed in 44% of neonates. For 2004-2009, the overall annual incidence of listeriosis varied from 0.25 to 0.32 cases per 100,000 population. Among Hispanic women, the crude incidence of pregnancy-associated listeriosis increased from 5.09 to 12.37 cases per 100,000 for the periods of 2004-2006 and 2007-2009, respectively; among non-Hispanic women, pregnancy-associated listeriosis increased from 1.74 to 2.80 cases per 100,000 for the same periods. Incidence rates of nonpregnancy-associated listeriosis in patients aged ≥ 65 years were 4-5 times greater than overall rates annually. CONCLUSIONS: Overall listeriosis incidence did not change significantly from 2004 through 2009. Further targeted prevention is needed, including food safety education and messaging (eg, avoiding Mexican-style cheese during pregnancy). Effective prevention among pregnant women, especially Hispanics, and older adults would substantially affect overall rates.

Changing Diagnostic Testing Practices for Foodborne Pathogens, Foodborne Diseases Active Surveillance Network, 2012-2019.

Background: Pathogen detection has changed with increased use of culture-independent diagnostic tests (CIDTs). CIDTs do not yield isolates, which are necessary to detect outbreaks using whole-genome sequencing. The Foodborne Diseases Active Surveillance Network (FoodNet) monitors clinical laboratory testing practices to improve interpretation of surveillance data and assess availability of isolates. We describe changes in practices over 8 years. Methods: During 2012-2019, 10 FoodNet sites collected standardized data about practices in clinical laboratories (range, 664-723 laboratories) for select enteric pathogens. We assessed changes in practices. Results: During 2012-2019, the percentage of laboratories that used only culture methods decreased, with the largest declines for Vibrio (99%-57%) and Yersinia (99%-60%). During 2019, the percentage of laboratories using only CIDTs was highest for Shiga toxin-producing Escherichia coli (43%), Campylobacter (34%), and Vibrio (34%). From 2015 to 2019, the percentage of laboratories that performed reflex culture after a positive CIDT decreased, with the largest declines for Shigella (75%-42%) and Salmonella (70%-38%). The percentage of laboratories that routinely submitted isolates to a public health laboratory decreased for all bacterial pathogens examined from 2015 to 2019. Conclusions: By increasing use of CIDTs and decreasing reflex culture, clinical laboratories have transferred the burden of isolate recovery to public health laboratories. Until technologies allow for molecular subtyping directly from a patient specimen, state public health laboratories should consider updating enteric disease reporting requirements to include submission of isolates or specimens. Public health laboratories need resources for isolate recovery.

Ten-year trends and risk factors for non-O157 Shiga toxin-producing Escherichia coli found through Shiga toxin testing, Connecticut, 2000-2009.

BACKGROUND: The epidemiology over time of non-O157 Shiga toxin-producing Escherichia coli (STEC) is unknown. Since 1999, increasing numbers of laboratories in Connecticut have been testing for ST rather than culturing for O157, enabling identification of non-O157 STEC. METHODS: Beginning in 2000, Connecticut laboratories were required to submit ST-positive broths to the State Laboratory for isolation and typing of STEC. The ratio of non-O157:O157 from laboratories conducting ST testing was used to determine state-level estimates for non-O157 STEC. Patients with STEC were interviewed for exposure factors in the 7 days preceding illness. Incidence trends, clinical features, and epidemiology of non-O157 and O157 STEC infections were compared. RESULTS: From 1 January 2000 through 31 December 2009, ST testing detected 392 (59%) of 663 reported STEC infections; 229 (58%) of the isolates were non-O157. The estimated incidence of STEC infection decreased by 34%. O157 and the top 4 non-O157 serogroups, O111, O103, O26, and O45, were a stable percentage of all STEC isolates over the 10-year period. Bloody diarrhea, hospitalization, and hemolytic uremic syndrome were more common in patients with O157 STEC than in patients with non-O157 STEC infection. Exposure risks of patients with non-O157 STEC infection differed from those of patients with O157 STEC infection primarily in international travel (15.3% vs 2.5%; P < .01). Non-O157 types differed from each other with respect to several epidemiologic and exposure features. CONCLUSIONS: Both O157 and non-O157 STEC infection incidence decreased from 2000 through 2009. Although infection due to O157 is the most common and clinically severe STEC infection, it accounts for a minority of all clinically significant STEC infections. STEC appear to be a diverse group of organisms that have some differences as well as many epidemiologic and exposure features in common.

Laboratory practices for the identification of Shiga toxin-producing Escherichia coli in the United States, FoodNet sites, 2007.

Clinical laboratory practices affect patient care and disease surveillance. It is recommended that laboratories routinely use both culture for Escherichia coli O157 and a method that detects Shiga toxins (Stx) to identify all Stx-producing E. coli (STEC) and that labs send broths or isolates to a public health laboratory. In 2007, we surveyed laboratories serving Foodborne Diseases Active Surveillance Network sites that performed on-site enteric disease diagnostic testing to determine their culture and nonculture-based testing practices for STEC identification. Our goals were to measure changes over time in laboratory practices and to compare reported practices with published recommendations. Overall, 89% of laboratories used only culture-based methods, 7% used only Stx enzyme immunoassay (EIA), and 4% used both Stx EIA and culture-based methods. Only 2% of laboratories reported simultaneous culture for O157 STEC and use of Stx EIA. The proportion that ever used Stx EIA increased from 6% in 2003 to 11% in 2007. The proportion that routinely tested all specimens with at least one method was 66% in 2003 versus 71% in 2007. Reference laboratories were less likely than others to test all specimens routinely by one or more of these methods (48% vs. 73%, p=0.03). As of 2007, most laboratories complied with recommendations for O157 STEC testing by culture but not with recommendations for detection of non-O157 STEC. The proportion of laboratories that culture stools for O157 STEC has changed little since 2003, whereas testing for Stx has increased.